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Tool rids wireless sensor nets of battery

Posted: 16 Nov 2007 ?? ?Print Version ?Bookmark and Share

Keywords:wireless sensor networks? IEEE 802.15.4? transceiver? Zigbee? mesh technology?

No wires and no batteries; now there's a combination. It's the promise of GreenPeak Technologies with a battery-free solution for ultralow-power wireless sensor and control networks based on the IEEE 802.15.4 standard.

The target, according to GreenPeak Technologies, is to leverage three key technologies and develop chips and modules for sensor applications that would operate without power cabling or batteries. The requisite technologies are an ultralow-power wireless transceiver and sensor interface design with efficient power-up and power-down modes that dramatically reduce power consumption; an energy-harvesting interface that lets the modules use power provided by external solar, electromagnetic and piezoelectric transducers; and a mesh technology that lets designers create extended sensor networks without the need for battery-powered or cabled routing nodes.

The company said its mesh technology is self-healing and self-forming, making the approach easy and inexpensive to install. And each device in the GreenPeak network can act as a repeater for other wireless devices, letting the network span larger distances.

Unlike competitive mesh solutions, which require battery power or cabling for the main routing nodes, GreenPeak networks tap smart power-up/power-down and synchronization techniques that enable all mesh nodes to operate in low-power mode.

Promising solution
Its name may be new, but GreenPeak's roots go back a couple of years to the formation of Xanadu Wireless, a venture-capital-backed fabless chip group formed to develop IP, chips and modules for the wireless sensor market. Xanadu's relaunch as GreenPeak followed its July purchase of Ubiware, a startup focusing on related Zigbee-type devices for monitoring and control sensor networks, for an undisclosed sum.

GreenPeak's co-founder and CEO, Cees Links, helped pioneer WLAN technology while at such companies as NCR, AT&T, Lucent and Agere, and is a founding member of the IEEE 802.11 Working Group and the Wi-Fi Alliance. "Zigbee-type sensor networks are clearly the 'third wave' of wireless, but we have a fundamental problem: The elimination of wires really needs to go hand-in-hand with taking the maintenance issue associated with batteries out of the equation," said Links. "Otherwise, people will just not buy into this. Half a solution is no solution."

Links said GreenPeak is sampling its low-power communications technology as a Lime modulea 5cm or smaller electronic component that OEM customers can integrate into their products. The standalone comms system integrates a transceiver, antenna and low-power mesh network software. It also features a transmit power amplifier that, according to Links, delivers four times the transmission range of non-amplified products without adversely affecting power requirements.

The module's software can be configured to manage the power of various energy-harvesting devices, though Links said the company does not do energy harvesting as such. He added that the package meets the requirements of Zigbee-Pro 2007, the latest version of the standard, which he expects the Zigbee Alliance to send out for balloting soon.

Lowering system cost

OEMs will also be able to add their own applications to the module, eliminating the need for an external processor and hence lowering total system cost.

A starter kit and development suite that includes graphical network visualization and control panel source code is now available. GreenPeak is already working on an integrated device that would incorporate all functions of the current module, and it is developing a full tool chain to support OEM integration.

GreenPeak technology maximizes system integration while minimizing power consumption, complexity, size and cost.

Links acknowledged that various other companies are offering some of the four elements (the three noted above, plus standards compliance) needed for developing wireless sensor nets, but said none has the full slate of capabilities. "And some of these companies are just talking about it or thinking about it," he said.

He said he doesn't think GreenPeak will compete with established players in the Zigbee or 802.15.4 space, such as TI, Freescale or Ember Corp. "We are coming at this from a different perspective--focusing on end nodes--and not as a means to sell unit volumes of MCUs or processors," Links said.

Nevertheless, GreenPeak's target markets are the same as for other members of the Zigbee Alliance: home automation, building automation, asset management, health care, and safety and security.

- John Walko
EE Times Europe

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